The Knot Garden, Linbury Studio Theatre, Royal Opera House, London

The Knot Garden is so 1970. Love and protest, civil rights, gay liberation. The issues just keep coming at you. Denise, "a dedicated freedom-fighter", has to be disabled, too; Dov is not just gay, but a screaming queen; his lover, Mel, is not just black, but a poet. And then there's Mangus. He's Prospero, man of power, of dreams - the opera's psychotherapist. And he has his work cut out. His wife, Thea, says things like: "Where I touch the tap-root to my inward sap."

The Knot Garden is so 1970. Love and protest, civil rights, gay liberation. The issues just keep coming at you. Denise, "a dedicated freedom-fighter", has to be disabled, too; Dov is not just gay, but a screaming queen; his lover, Mel, is not just black, but a poet. And then there's Mangus. He's Prospero, man of power, of dreams - the opera's psychotherapist. And he has his work cut out. His wife, Thea, says things like: "Where I touch the tap-root to my inward sap."

She's a gardener, you see, and this, her "garden of Eden", symbolises the opera's sexual nature. It's also Prospero's island, because that serves Sir Michael Tippett's Jungian take on The Tempest; and it's a "knot garden" - a maze of confusions. Which is what you are more than likely experiencing as you read this.

Most of us have long since admitted defeat over Tippett's opera libretti in general and this one in particular. On the one hand, they lay bare his teeming imagination, his inquisitive mind, his conscientious objections; on the other, they are self-serving and pretentious. The idea that an audience - any audience - could follow, let alone unpick, The Knot Garden's knotty form, its myriad allusions and its multi-layered subtext, is at the very least breathtakingly optimistic.

But that was part of Tippett's charm, I guess. The dottiness came with the visionary. Rather more surprising, though - and fatal to the work as a piece of viable drama - is that Tippett, the great humanist, should have failed so utterly to engage us with any of the characters. Archetypes, all of them. You really can't see or hear them for the psychobabble. And we have to. We have to engage and we have to care on some level.

There are moments when the music invites us to do so. When Dov (the caring homosexual, the "fairy" Ariel) comforts the troubled Flora, he does so through music. She sings the touching refrain of a Schubert song ("My love's so fond of green"); he sings the blues ("I was born in a big town, in a home without a garden"). There's a connection. And we, the audience, connect. Music comes close to saving The Knot Garden. Tippett's imperative score (conducted here by Michael Rafferty) is driven forward on the hard-edged shake, rattle and roll of percussion; shrill, wiry strings suggest Ariel setting the air vibrating; the redundant twang of electric guitar somewhat cheesily (very Sixties) suggests the urban jungle.

That's something that Michael McCarthy, the director, and Jane and Louise Wilson, the designers, have caught well in this co-production between the Royal Opera and Music Theatre Wales. Roving video projections snap back and forth between Tippett's "Eden" and its concrete urban context. The video screens themselves are reconfigured into "the labyrinth" of Act II. There is a great sense of mental and emotional flux in the physicality of the staging.

The seven-strong cast are full-on: Jeremy Huw Williams (Mangus) has the forthright projection that marks out any master of ceremonies; Elizabeth Watts (Flora) duly floats her dreams, hopes and fears; Helen Field gamely hurls out Denise's contorted vocal lines, but too few of her words; Rodney Clarke and a bravely uninhibited Christopher Lemmings lend their Beckett-like charms to Mel and Dov, respectively; and as the married couple, Faber and Thea, Gwion Thomas and Lucy Schaufer polarise the interests of progress and ecology. Schaufer - so good in ENO's On the Town - is terrific here: great presence and real engagement against the odds. But in the end, when Faber says, "I am all imagination", you realise that's the problem. We can never get into Tippett's head. The Knot Garden always needs replanting.